Apparatus for expanding metal tubes



Dec. 12, 1933. A. s'rElNEcKE 1,939,526

' APPARATUS .FOR EXPANDING METAL TUBES Filed Jan. 11. 1930 6Sheets-Sheet l Dvb: f Hy.;

.Dec- 12, 1933- A. STEINECKE '1,939,526

APPARATUS FOR EXPANDING METAL TUBES Filed Jan. '11, 1930 6 Sheets-Sheet2 www@ l2, 1933. A. STEINECKE 1,939,526

APPARATUS FOR EXPANDING METAL TUBES ffy, 7

l2, 1933. A. s'rglNEcKE 515939526 APPARATUS FOR EXPADlNG METAL TUBES LFiled Jan. ll, 1950 6 Sh'elfcs-Sheet 1.A

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I C K Ef/ f/ y f Deu. 12, 1933. A. STEINECKE 1,939,525

' APPARATUS FOR EXIQANDINGl METAL TUBES Filed Jan. 11, 1930 6Sheets-Sheet 5 MAMMA De@ l2, 1933. A. ,STEINECKE 1,939,526

I APPARATUS FOR EXPANDING METAL TUBES Filed Jan. 11, 1930 6 Sheets-Sheet6 www@ Patented Dec. 12, 1933 PATENT OFFICE APPARATUS FOlTt E XlANDINGMETAL UBE Adolf Steinecke, Komotau, Czechoslovakia Application January11,

1930, Serial No. 420,218,

and in Germany January 18, 1929 12 claims.

The invention relates to a process and apparatus for expanding metaltubes over their entire length by means of oblique rolls.

Hitherto, tubes, especially those having a relatively large diameter andthin walls, have been produced on oblique roller mills, the rolls ofwhich, are provided with working surfaces directed towards one anotherat a relatively pronounced angle in the plane extending through the axisof the rolls and the axis of a tube undergoing treatment by the rolls. Acorrespondingly tapered mandrel disposed within the tube and between thesaid rolls is arranged to counteract the whole of the working pressureof the rolls including the side thrust thereof. It is necessary that themandrel does not change its predetermined position between the rolls asany displacement thereof relative to the rolls considerably affects theworking of the rolls and the dimenlsions of the work produced. The firstrequirement for a reliable rolling operation is therefore the provisionof means whereby thel mandrel is maintained in a'predetermined positionwith respect to the working surfaces of the rolls during the wholeworking process, so that uniformity of the work produced by the rolls isensured. As the mandrel is disposed within a tube undergoing treatmentthe internal diameter of the tube necessarily imposes limitations uponthe means employed for securing the mandrel in its working position.Heretofore the mandrel has always been secured to a rod which, dependingupon the length of the tubes to be rolled and the degree of pressure ofthe rolls, is subject to varying degrees of alteration in length. Theheating of a relatively long mandrel rod during the rolling processcauses changes in the length of the rod, even when the rod iswater-cooled, which consequently causes a displacement ot the man- 40drei between the rolls. In order-to overcome this difficulty, fineadjustments for the mandrel are used which permit, by carefulobservation of the rolling process, correctionsv in the position of themandrel. The said corrections may be mad during the rolling operation.

This process necessitates, however, a somewha complicated apparatus andgreat attention therefore has to be paid to the rolling operations.

The present invention comprises a process for expanding metal tubes bymeans of obliquely disposed rolls characterized by the tubes beingexpanded and shaped to an oval conguration in cross-section betweenparallel working surfaces of rolls acting in conjunction with arelatively slishtlyconicaimandrelwiththelarg'- er end thereof in adirection corresponding to the direction of feed of the tube or betweenworking vsurfaces of rolls relatively slightly inclined towards oneanother in a direction correspondingv to the direction of feed of thetube acting inconjunction with a cylindrical mandrel.

Further the present invention comprises a process according to thepreceding paragraph characterized by the tube after leaving the workingsurfaces of the rolls and mandrel, being 55 shaped to a circularcross-section by guide means disposed exteriorly or interiorly of thetube.

Again according to the present invention there is provided a rollingmill forcarrying out the process in accordance with either of the twopreceding paragraphs characterized by the provision of a hollow conicalguide having a circular or oval shaped mouth for the tubes for thepurpose of shaping the oval tubes produced by the rolls to a circularcross-section and wherein the said guide is constituted by a portion ofthe rolls or by a separate unit connected to the mill.

The method set out above necessitates an alteration in the diameter ofthe rolls and a corresponding alteration in shape of the mandrel, andthe disadvantageous alteration in theposition of the mandrel withrespect to the rolls vhitherto experienced, due either to variationsproduced to the length of the mandrel rod or the insecurity of locatingthe same under the relatively very heavy roller pressure or by the heat`generated during the rolling operation, does not affect the working ofthe rolls, and the operation of the mill is thereby simplified andcheapened. Further the faulty work hitherto caused by want .of carefulobservation in the usual method of working described above, iseliminated.

It has already been proposed with calibrating roller mills, to useobliquely disposed rolls provided with parallel working surfaces. Thisarrangement, however, has only been used in order to bring smallirregularities in the walls of tubes, for example at places where thewall is thicker than is desired, to the correct size and a stretching-of the wall at such places is thereby caused with consequential localincreases in the diameter of the tube.

In order to move the tube longitudinally over the mandrel by means ofthesaid oblique rolls, a relatively lighter pressure must be exerted uponthe wall of the tube between the rolls and the mandrel even on such,places where it is correctly'dimensioned. The local increases in thediameter ofthe tube produced as above described 110 constituteundesirable additional work and the tubes must therefore subsequently bepassed through a dimensioning rolling mill in order to obtain thedesired uniform diameter of the tubes.

Further it has been'proposed` in the finishing process of rolling tubes,to roll the same alternately circular and oval in cross-section upon amandrel, when both the section of the mandrel and that of the diameterof the rolls are arranged to correspond with the alterations of thetubes from circular to oval, or in a further arrangement from an ovalsection to a similar oval section displaced'therefrom about the axis ofthe tube by an angle of 90.

The present invention, on the contrary, provides a continuous stretchingof the substance of the walls of the tube over the whole length thereof,and an expansion of the tube between a mandrel and rolls co-actingtherewith.

The invention is illustrated in the accompanying drawings of whichFigure 1 illustrates diagrammatically details of a rolling millconstructed in accordance with the present invention.

Figure 2 is a similar view to Figure 1, but illustrating a modificationof this invention.

Figure 3 illustrates a cross-section of the tube shownin Figure 1 with amandrel disposed in the interior thereof.

Figure 4 illustrates in longitudinal section a guide for restoring thetubes of oval cross-section .which leave rolls to a circularcross-section.

Figure 5 illustrates in end elevation a modified form of guide.

Figure 6 illustrates in longitudinal section the guide illustrated inFigure 5 in conjunction with the rolls and mandrel of a rolling millconstructed in accordance with this invention and with a tube in theworking position therein.

Figure 7 is a view similar to Figure 6 of a modified form of guide.

Figure 8 is a view similar to Figure 6 of a modified form of guide.

Figure 9 is a View similar to Figures 6 and 8 of afurther modified formof guide.

Figure 10 is a View similar to Figure 1 but illustrating an internalform of guide for restoring the tubes to a circular cross-section.

Figure 11 is a longitudinal' sectional view at right angles to Figure10.

Figure 12 is a transverse section of Figure 11.

Figure 13 is a View similar to Figure 5 but showing another form ofguide.

Figure 14 is a longitudinal section similar to Figure 4.

Figure' 15 is a view similar to Figure 13 but showing a further modifiedform of guide.

Referring to Figure 1 of the drawings, the working surfaces a of therolls b are disposed parallel to one another so that the space betweenthe rolls remains constant.. The mandrel c is made slightly conical andthe larger end is disposed in a direction corresponding to the directionof feed of the tubes.4

Preferably, the larger end of the mandrel is of a diameter which ensuresthe required reduction in .hickness ofjthe walls of the tube. Theworking length of the mandrel is dependent, on the one hand, upon thecircumference of the eX- panded tube and, on the other hand, on thecircumferential speed of'the rolls, that is to say, the stretching ofthe circumference of the tube must increase as the tube passes the'rolls at about the same rate as the rate of increase in circumferentialspeed of the working faces of the rolls in order that the tube may notbe twisted.

Instead of the disc rolls, illustrated in the drawings, so-called barrelrolls may if necessary be used. As shown by Figure 2 the workingsurfaces of the rolls may be disposedat a slight inclination to the axisof the mandrel in which case the mandrel is purely cylindrical.

Preferably the "smaller distance between the rolls, which is between theworking surfaces of the edges thereof Where the tube leaves the rolls,is chosen corresponding to the required reduction in thickness of thewalls of the tube. As the space between the working surfaces of therolls remains the same or is reduced an increase of the diameter of thetube in this direction is not possible, consequently, the tube d asshown in Figure 3 assumes a marked oval form in crosssection as shown atd1 and retains this shape until it passes outside the range of theworking surfaces of the rolls.

A tube leaving' the expansion rolls is, as already stated, markedly ovaland requires to be formed into a cylindrical shape. For this purpose, atube may, for example, after leaving the expansion rolls be passedthrough a conical guide, the larger internal diameter of whichcorresponds to the larger external diameter of the oval tube, and thesmaller diameter of which to the external diameter of the tube whenrestored toa cylindrical shape. The construction of the conical guidemay be of various forms. The guide may comprise a closed movable orstationary funnel. The first construction; Figure 4, is preferred toavoid sliding friction.

The walls of the conical guide may also be formed by roller g as shownby Figures 5 and 6. These rollers may all run idly on their axes or bedriven by spindles provided thereon, or again some may be driven and theremainder run idly on their axes.

As shown in Figure 7 one roller g1 is driven to force the tube, afterleaving the rolls through the conical guide. The rollers are arranged tobe adjustable and interchangeable according to the diameter of the tubeto be rolled. It is to be understood that any number of rollers may bearranged around the circumference of the conical guide, as required andin the examples shown in Figures 5 and 6, four rollers are used, equallyspaced around the circumference. The axes of the rollers may be inclinedrelatively to the axis of the tube as shown in Figures 8 and 9 for thepurpose of imparting a longitudinal feeding `movement to the tube and amandrel f may be disposed within the tube. The same effect may /beobtained by providing the rolls b with special x working surfaces m,Figures 10 to 12, which are arranged to act upon the tube as it passesover the cylindrical portion l1 of the mandrel l.

Instead of the above described movable external guide for forming thecylindrical tube, internal guide means or a shaping device in the formof a mandrel f Figures 6 to 9, or of a mandrel l, connected to the rollmandrel c, Figures 10 and 11, may be used.

Instead of the movable guides a stationary shaping device, a closedstationary funnel e, Figures 13 and 14 may be used the wall of which maybe discontinuous as shown in Figure 15, so that only relatively fewguide pieces e1 are used.

I claim:

1. An apparatus for expanding metal tubes comprising obliquely disposedrolls, the working surfaces of which are parallel, a relatively slightlyconical mandrel disposed with the largenend thereof in a directioncorresponding to the direction of feed of the tubes and vguide meansexterior of the tubes for shaping the tubes to a -circularcross-section. y

E2. An apparatus for expanding metal tubes comprising obliquely disposedrolls, the working surfaces of which are parallel, a relatively slightlyconical mandrel disposed with the larger end thereof in a directioncorresponding to the direction of feed of the tubes and guide meanswithin the tubes fora shaping the tubes to a circular cross-section.

3. An-apparatus for expanding metal tubes comprising obliquely disposedrolls the working surfaces of which being relatively inclined towardsone .another in a direction corresponding to the direction of feed ofthe tube, a cylindrical mandrel and guide means exterior of the tubesfor shaping the tubes to a circular cross-section.

4. An apparatus for expanding metal tubes comprising obliquely disposedrolls the working surfaces of which being relatively inclined towardsone another in a direction corresponding to the directiony of feed ofthetube, a cylindrical mandrel and guide means Within the tubes forshaping the tubes to circular cross-section.

5. An apparatus for expanding metal tubes comprising obliquely disposedrolls, a mandrel between the rolls andl slightly inclined workingsurfaces towards the major axis of the tubes on one of them and astationary guide for rounding the tube.

6. An apparatus for expanding metal comprising obliquely disposed rolls,a mandrel between the rolls and slightly inclined working surfacestowards the major axis of the tubes on one of them and a hollow conicalguide formed of straight edged members.

7. An apparatus for expanding metal tubes comprising obliquely disposedrolls, a mandrel between the rolls and slightly inclined workingsurfaces towards the major axis'of the tubes on one of them, a hollowconical guide having a circular shaped mouth and a partly conical andpartly cylindrical mandrel disposed co-axially within the conical guide.

8. An apparatus for expanding metal tubes comprising obliquely disposedrolls, a mandrel between the rolls and slightly inclined workingsurfaces towards the major axis of the tubes on one of them, a hollowconical guide having an oval shaped mouth and a partly conical andpartly cylindrical mandrel disposed co-axially within the conical guide.

9. A tube expanding mill, comprising apair of skew rolls provided withconical working faces formed to engage the outer surface of the wall ofa tube parallel to its axis, and a mandrel between the rolls providedwith a conical working face tapering outwardly in the directionofmovement of a tube through the mill and positioned to cooperate withsaid roll faces to reduce the wall thickness and enlarge the diameter ofthe tube, the pass formed by said rolls and mandrel being of constantdraft regardless of normal variations in the longitudinal position ofthe mandrel with relation to the rolls.

10. A tube expanding mill comprising obliquely disposed rolls havingsurfaces constituting a working face formed to engage the outer surfaceof the wall of a, tube, and a mandrel between `the rolls provided with aworking face positioned to cooperate with said roll face to reduce thewall thickness and enlarge the diameter of the tube, one of said workingfaces being slightly inclined to the axis of the tube, the other of saidworking faces being substantially parallel to the axis of the tube,whereby the pass formed by said rolls and mandrel is of constant draftregardless of variations in the longitudinal position of the mandrel.

11. A tube expanding mill comprising obliquely disposed rolls and amandrel, said rolls and mandrel havingworking surfaces one on said rollsand the other on said `mandrel cooperating to reduce the wall thicknessand enlarge the diameter of the tube by giving it an oval cross section,one of said working surfaces being inclined to the axis of the tube,-the other being parallel to the axis of the tube, whereby the pass'formed by said rollsA and mandrel is of constant draft regardless ofvariations in. the longitudinal position of the mandrel, and roundingmeans receiving the oval tube from the rolls and mandrel.

12. An apparatus for expanding metal tubes comprising obliquely disposedrolls as a unit, a mandrel between the rolls as another unit and aworking surface on one of said units slightly inclined toward the majoraxis of the tube and working surfaces on the other of them parallel tosaid axis, said surfaces cooperating for thinning and expanding the tubeinto oval cross section of constant draft regardless of variations inthe longitudinal position of the mandrel, and conical rounding surfacesreceiving the oval tube leaving the rolls. i

ADOLF STEINECKE.

